Polymeric compounds of dibenzylidenebenzenediacetonitriles and process of preparing same



United States Patent Ofilice 3,312,66 Patented Apr. 4, 1967 RH m R a R RL ON R wherein R is a monovalent substituent selected from the groupconsisting of hydroxy and hydroxyalkoxy, acyloxy, sulfonoxy, andepoxyalkoxy groups containing from 3 to 18 carbon atoms,

R and R are monovalent substitutents selected from the group consistingof hydrogen, hydroxy, hydroxyalkoxy, epoxyalkoxy, halogens, nitro, andalkoxy, aryloxy, acyloxy, sulfonoxy, acyl and alkyl groups containingfrom 1 to 18 carbon atoms, with all hydroxy groups being in the metaorpara-positions,

X is a monovalent substituent selected from the group consisting ofhalogens, nitro and methyl groups, and

m is an integer from t0 4, inclusive.

It has now been found that dibenzylidenebenzenediacetonitriles can betransformed into new and novel polymers. The novel products of thepresent invention can be prepared by the homopolymerization of themonomeric benzenediacetonitriles. This type of polymerization is inducedand effected solely by the application of radiant energy to themonomeric compounds. More specifically, the present inventioncontemplates the synthesis of homopolymers by subjectingbenzenediacetonitriles, while in the solid crystalline state, to radiantenergy having a wave length less than about 6,000 Angstrom units, andpreferably between about 3,000 and 6,000 Angstrom units. When compoundsof this type, whether substituted or unsubstituted, are exposed toradiant energy having the requisite short wave length, they react withthemselves to form insoluble, high melting, polymeric compounds. Theseproducts differ materially from the monomeric compounds, which arerelatively soluble in a number of organic solvents and are generallycolored.

The polymeric materials may be readily converted to the originalmonomeric form merely by the application of heat. Thus the methods andproducts of the present invention are well suited to a variety ofphotographic and heat printing processes. In addition, the polymericproducts may be used as plasticizers or resin additives which can beincorporated in soluble monomeric form and then rendered insoluble byexposing them to light. Thus they can be employed to provide lightstabilization or other light actuated beneficial efiects to resinousmaterials. The marked difference in solubility between the monomeric andlight-produced polymeric forms of these compounds renders themparticularly adaptable for use in photoresist compositions. Also,because of the long conjugated electronic system present in themonomeric form but absent in the polymeric form, these compounds may beemployed in applications involving elec trical conductivity. Thisparticular utility is based on the interconversion between conductingand insulating forms by means of heat and light. The insoluble polymericforms may also be used to advantage in highly resistant coatingformulations.

It has been found that a minimum temperature of about 260 C. is requiredto effect the depolymerization. In

other words, the conversion of the homopolymers to monomeric compoundscan be effected at temperatures between about 260 C. and thedecomposition points of thehomopolymer and its monomer.

The exact mechanism of the reaction involved is not known. However, itis believed that two ethylene groups in adjacent molecules of thebenzenediacetonitriles combine to form a cyclobutane ring which thenserves as the connecting link between two of the original molecules.Thus it is postulated that one ethylene group of each 5 molecule reactswith an ethylene group of an adjacent molecule, and the other ethylenegroups, in turn, react with another pair of adjacent molecules to formadditional cyclobutane rings. The molecular structure of the resultantpolymer is believed to be rather well rep-resented by the followingstructural formulae:

anti

By reference to the above formulae, it will be noted that in I thenitrile groups are in the l, 2 positions, whereas in II they are in thel, 3 positions. Also, it will be noted that Formula I represents a blocktype of structure, whereas II represents a staggered type of structure.The actual position of the nitrile groups in the cyclobutane rings hasnot been positively determined, but it is well established that theproducts contain a large number of dicyano cyclobutane rings. Theformulae shown in I and II, above, are somewhat diagrammatic, and theproducts can consist of either type of these structures or combinationsor modifications of them. In any event, it is believed that thepolymeric product is a complex threedimensional molecule containingalternate benzene and cyclobutane rings. This assumption as to theparticular arrangement of the polymeric molecule seems to be substitutedby ultraviolet spectral and X-ray analyses. While the above formulaerepresent the present understanding of the construction of the polymericmaterials obtained,

it will be readily appreciated that the invention is not restricted tothis supposition, but that it is directed to homopolymers ofbenzenediacetonitriles regardless of their particular stereoarrangement.

The polymeric products of the present invention have a molecular weightbetween about 3,000 and about 30,000. Thus they are formed by thepolymeric combination of from 6 to about 60 units of the monomericstarting material. This molecular weight range has been confirmed by theintrinsic viscosity of the products. For example, the intrinsicviscosity of a sulfuric acid solution of the product produced by theaction of incandescent light on alpha,alpha'-bis(4 acetoxy 3methoxybenzylidene)-p-benzenediacetonitrile was found to be 0.3. The

approximaterelationships between intrinsic viscosity and,

molecular weight are known for many polymers. By applying several ofthese relationships to the 0.3 intrinsic viscosity value, one obtainsvalues in the 3,000 to 30,000 molecular weight range.

The radiant energy required to effect the polymerization of the presentinvention must have an average Wave length less than 6,000 Angstromunits, and preferably has a wave length between about 3,000 and 6,000Angstrom units. Thus, various types of light (either natural orartificial) can be employed. For example, strong sunlight or light froman incandescent bulb, with or without suitable filter, is completelysatisfactory. Likewise, ultra;- violet light, gamma rays, X-rays, andany other relatively short wave radiant energy can be readily utilizedin accordance with the present invention. generated by various types ofcommercially available lamps, including ultraviolet lamps, fluorescentlamps, standard incandescent bulbs, and the like. The rate of reactionvaries considerably with different crystalline structures, from onecompound to another and also with the type and intensity of the radiantenergy. In most instances, it is preferred to use incandescent light;but, in some cases, the reaction may be materially accelerated by theapplication of other types of light. Additionally, the starting compoundcan, in some particular cases, be advantageously exposed to two or moretypes of radiant energy. For example, one may concurrently expose thestarting compound to X-rays and to the rays emitting from anincandescent bulb.

The presentreaction may be conducted in a variety of ways. It is onlynecessary that the starting compound be in the solid crystalline stateand exposed to asource of radiant energy. When relatively small amountsof a particular compound are required, or when it is desired to utilizebatch operations, the compound being polymerized is placed in a tumblingvessel which is rotated while being exposed to the radiant energy. Thetumbler can be any conventional type of apparatus, such as a Sweetiebarrel, etc. Alternately, the starting compound can be placed in asuitable container which is transparent to the radiant energy employed.The container, such as a large cylin- The light may be 5 alcoholicpotassium hydroxide.

drical bottle, can then be closed, and any danger of contamination fromthe atmosphere is thus effectively eliminated.

The present process is also admirably well suited to continuousoperation. The material to be treated is merely introduced into aconventional belt-type drier and passed into close approximation with aseries of lamps providing the necessary short wave radiant energy. Sincethe reaction requires only light for its completion, there is no need tomaintain close temperature control.

As pointed out above, the rate of reaction is primarily dependent uponthe type and intensity of radiant energy. General speaking, the rate ofreaction increases directly with the intensity of applied energy. Thusit is generally preferred to utilize high energy levels. These can beobtained by positioning the source of energy very close to the materialbeing treated, or by the use of reflectors, concentrating lenses, andthe like. The temperature has little, if any, effect upon the rate ofreaction. It is only necessary that the starting material be maintainedin a solid crystalline state. The particle size of the starting materiallikewise has no significant effect upon the rate of reaction. Whenrelatively large particles of the starting material are employed, it hasbeen noted that the product chips or spalls from, the compound beingprocessed. This action thus exposes additional starting material to theradiant energy. In most cases, however, it is preferred to utilize astarting material having a particle size between about 40 and 300 mesh.

The invention and the manner in which it accomplishes its objects willbe more readily understood by reference to the following specificexamples of preferred embodiments thereof. The proportions in theseexamples and throughout the specification are given in parts by Weightunless otherwise indicated.

Example 1 A S-gram sample of alpha,alpha'-bis(4-acetoxy-3-methoxybenzylidene) p-benzenediacetonitrile elongated crystallineplatelets is placed in an 8-ounce, clear glass, square bottle, capped,and slowly rotated at a distance of about three inches from a ZOO-wattincandescent light bulb. After approximately 18 hours, the sample turnsfrom yellow to white. This resultant white material is insoluble in thefollowing boiling solvents: water, hydrochloric acid, aqueous sodiumhydroxide, acetone, ethanol, ethyl acetate, methyl cellosolve, dioxane,triethylamine, pyridine, chlorobenzene, trichloroacetic acid,1,1,2-trichloroethane, phenylacetonitrile, dimethylformamide, dimethylsulfoxide, naphthalene, diethyl carbitol, dibutyl carbitol, sulfolane,hexamethylphosphoramide, and a 20% solution of lithium chloride indimethylformamide. It is also insoluble in camphor (at its meltingpoint), in alpha,alpha'-dibenzylidene-p-benzenediacetonitrile (at itsmelting point), alpha,alpha di-(l-thenylidene)-p-benzenediacetonitrile(at 310 C.), and alpha,alpha-divanillylidene-p-benzenediacetonitrile (at310 C.). It is soluble in concentrated sulfuric acid and dissolvesslowly in The material melts at about 320 C. and gives the followinganalysis: Calculated for (C H O H C, 70.85; H, 4.76; N, 5.51. Found: C,70.95, 71.00; H, 4.91, 4.73; N, 5.48, 5.60.

Infrared and ultraviolet spectra indicate the disappearance of theethylenic double bonds present in the yellow material.

Example 2 A sample of the white product obtained, in accordance withExample 1 is heated at about 78 C. for approximately 18 hours with asolution prepared from one gram of potassium hydroxide pellets and 50ml. of ethyl alcohol. Then 40 ml. of water is added, the mixture warmed,then filtered. The liquors are acidified by the addition of hydrochloricacid, and the precipitate which formed is collected and dried. Theprecipitated material melts at 240-24l (1., identifying it asalpha,alpha-bis(4-acetoxy-3-meth-oxybenzylidene)-p-benzenediacetonitrile, the starting material ofExample 1.

Example 3 Another sample of the white product from Example 1 is heatedfor about seven minutes at a temperature in the range of from 313 C. to327 C. After cooling, the residue is dissolved in hot1,1,2-trichloroethane. Upon cooling, crystals separate which areidentified as alpha, alphabis(4-acetoxy-B-methoxybenzylidene)-p-benzenediacetonitrile, thestarting material used for the preparation of the .homopolymer.

Example 4 A layer of the crystals of alpha,alpha'-bis(4-acetoxy-3-methoxybenzylidene)-p-benzenediacetonitrile approximately onemillimeter in depth is exposed to the ultraviolet radiation from aGeneral Electric H100BL4 lamp. (This lamp radiates 99% of its energy inthe 3,200-4,000 A. region.) A white solid is obtained which is identicalto that obtained from the exposure with an incandescent lamp asdescribed in Example 1.

p The lamp is focused through a series of Pyrex lenses, and theintensity of the beam is measured by uranyl oxalate actin-ometry, usingthe method recommended by G. T. Rogers in Chemistry and Industry, page572 (1956). Using this calibrated beam, samples of alpha,alpha-bis- (4acetoxy 3-methoxybenzylidene)-p-benzenediacet0ni trile are exposed forvarying periods of time, and the amount of material produced that wasinsoluble in 1,1,2- trichloroethane is measured. In this manner, thequantum yield is found to be about 0.7 double bond per photon.

Example 5 A layer of the crystals of alpha,alpha'-bis(4-acetoxy-S-methoxybenzylidene)-p-benzenediacetonitrile about one millimeter thickis exposed to sunlight for about six hours. Again the insoluble whitematerial observed on irradiation with incandescent light is obtained.

Example 6 A substantial repetition of the processes of Examples 4 and 5,using emanations from a fluorescent lamp instead of ultraviolet light orsunlight, also yields the insoluble homopolymers of alpha,alpha' bis(4acetoxy-3-methylbenzylidene -p-benzenediacetonitrile.

Example 7 Crystals of alpha,alpha bis(4 acetoxy 3methoxybenzylidene)-p-benzenediacetonitrile are placed in the beam ofX-rays, copper K-alpha radiation. The X-ray dilfraction pattern obtainedchanges on exposure, indicating that the transformation to thehomopolymer is produced by these X-rays.

Example 8 When a hot sodium of alpha-alpha'-bis(4-acetoxy-3-ethoxybenzylidene) p benzenediacetonitrile in acetic anhydride isallowed to cool, two difierent dimorphous crystal forms are obtained.One form consists of small crystals roughly the same size in the threedimensions; the other is in the form of large coarse needles severaltimes as long as wide. The small crystals are readily converted to thepolymeric form by exposing them to incandescent light, while the coarseneedles are most conveniently converted by first warming them to atemperature between about 180 C. and about 240 C., followed by exposureof the heat-treated material to light.

Example 9 In a manner similar to that described in Example 2, thecrystals ofalpha-alpha'-bis(4-acetoxy-3-ethoxybenzylidene)-p-benzenediacetonitrile,having substantially the same size in three dimensions, are convertedinto a polymeric material by exposure to an ultraviolet source.

Example 10 When a layer of crystals of -alpha-alpha'-bis(4-propionoxy-3rnethoxybenzylidene)-p-benzenediacetonitrile is exposed to illuminationfrom fluoroescent lights, a polymeric product is obtained identical withthat formed in Examples 1 and 4.

The corresponding homopolymers of otherdibenzylidenebenzenediacetonitriles can be obtained in like manner bysubjecting the monomeric materials to radiant energy of the requisitewave length. For example, ultraviolet light X-ray can be employed in thepreparation of the homopolymers of:

-alpha,alpha'-bis [4-acetoxy-3-(2',3-epoxyalkoxy) -benzylidene]-p-benzenediacetonitrile,

alpha-alpha-bis 4-acetoxy-3-chlorobenzylidene -pbenzenediacetonitrile,

alpha,alpha'-bis (4-acetoxy-3-nitrobenzylidene -pbenzenediacetonitrile,

alpha,alpha'-bis (4-acetoxy-3-benzyloxybenzylidenep-benzenediacetonitrile,

alpha-alpha'-bis (4-benzoxy-3-rnethoxybenzylidenep-benzenediacetonitrile,

alpha,a'lpha'-bis(4-acetoxy-3-phenoxybenzy1idene)-pbenzenediacetonitrile,

alpha-alpha'-bis 3-methoxy-4-sulfonoxybenzylidenep-benzenediacetonitrile,

alpha,alpha'-bis 4-acetoxy-3 -methylbenzylidene)-pbenzenediacetonitrile,

alpha,alpha'-bis 4-acetoxy-3-butylbenzylidene) -pbenzenediacetonitrile,

alpha, alpha-bis 4-acetoxy-3-allylbenzylidene) -pbenzenediacetonitrile,

alpha,alpha'-bis (4-acetoxy-3-octadecenylbenzylidene)p-benzenediacetonitrile,

alpha,alpha'-bis (4-acetoxy-3-octadecylbenzylidenep-benzenediacetonitrile,

alpha,alpha-bis 4-acetoxy-3 -methylbenzylidene -mbenze nediacetonitrile,

alpha,alpha'-bis (4-acetoxy-3-methylbenzylidene -obenzenediacetonitrile,

alpha,alpha'-bis (4-acetoxy-3-methylbenzylidene -pbenzenediacetonitrile,

alpha,alpha'-bis (4-propionoxy-3-methylbenzylidenem-benzenediacetonitrile,

alpha,alpha'-bis (4-ste aroyloxy-3-methylbenzylidene)p-benzenediacetonitrile,

alpha,alpha-bis (4-hydroxy-3-methy1benzylidene -pbenzenediacetonitrile,

alpha,alpha'-bis 4-acetoxy-3 -acetylbenzylidene -pbenzenediacetonitrile,

alpha,alpha'-bis (4-acetoxy-3-stearoylbenzylidene-pbenzenediacetonitrile,

alpha, alpha-bis (4-acetoxy-3 -methoxybenzylidene -p-2-methylbenzenediacetonitrile,

alpha,alpha-bis 4-acetoXy-3-methoxybenzylidene) -p-2'-bromobenzenediacetonitrile, alpha,alpha'-bis4-acetoxy-3-methoxybenzylidene -p- 2,5 -dimethylbenzenediacetonitrile,

alpha,alpha-bis (4-acetoXy-3 methoxybenzylidene) -p-2',

5'-dichlorobenzenediacetonitrile,

alpha,alpha'-bis (4-acetoXy-3-methoxybenzylidene) -p- 2',5-dinitrobenzenediacetonitrile,

alpha,alpha'-bis (4-acetoXy-3-rnethoxybenzylidene) -p-2',5'-dibromobenzenediaoetonitrile,

alpha,alpha'-bis (4-acetoxy-3 -methoxybenzylidene-ptetramethylbenzenediacetonitrile,

alpha,alpha'-bis 4-acetoxy-3-methoxybenzylidene) -m-4-methylbenzenediacetonitrile,

alpha,alpha-bis (4-acetoxy-3 -methoxybenzylidene -m-4-'-chlorobenzenediacetonitrile,

alpha,alpha'-bis (4-acetoXy-3-methoxybenzylidene) -m-4-nitrobenzenediacetonitrile,

alpha,alpha'-bis (4-acetoxy-3-methoxybenzylidene) -m-4-bromobenzenediacetonitrile,

alpha,alpha'-bis 4-acetoxy-3-methoxybenzylidene -m-2',6'-dichlorobenzenediacetonitrile,

alpha,alpha'-bis (4-acetoXy-3-methoxybenzylidene -p-2'-chloro-5-nitrobenzenediacetonitrile,

alpha,alpha-bis (4-acetoXy-3-methoxybenzylidene) '-o-4'-chlorobenzenediacetonitrile, and

unsubstituted dibenzylidenebenzenediacetonitriles.

Numerous modifications and additional compounds will readily Thus, whilethe invention has been described with particular reference to specificembodiments, it is to be understood that it is not limited thereto butis to be construed broadly and restricted solely by the scope of theappended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A homopolymer of a dibenzylidenebenzenediacetonitrile having amolecular weight of at least about 3,000.

2. A homopolymer of a dibenzylidene-p-benzenediacetonitrile having amolecular weight of at least about 3,000.

3. A homopolymer of alpha,alpha'-bis(4 acetoxy 3- methoxybenzylidene) pbenzenediacetonitrile having a molecular weight of at least 3,000.

suggest themselves to those skilled in the art.

4. A homopolymerof alpha,alpha'-bis(4-propionoxy-3-methoxybenzylidene)-p-benzenediacetonitrile having a molecular Weightof at least about 3,000.

5. A homopolymer of alpha,-alpha'-bis(4-butyroxy 3- methoxybenzylidene)p benzenediacetonitrile having a molecular Weight of at least about3,000.

6. A homopolymer of alpha,alpha'-bis(4 acetoxy- 3-ethoxybenzylidene)-p-benzenediacetonitrile having a molecular weight ofat least about 3,000.

7. A homopolymer of alpha,alpha'-bis(4-propionoxy- 3-ethoxybenzylidene)p benzenediacetonitrile having a molecular weight of at least about3,000.

8. A process for the formation of a dibenzylidenebenzenediacetonitrilehomopolymer which comprises subjecting the benzenediacetonitrile toradiant energy of a wave length shorter than about 6,000 Angstrom units.

9. A process for the formation of a dibenzylidenebenzenediacetonitrilehomopolymer which comprises subjecting the benzenediacetonitrile toradiant energy having a wave length between about 3,000 and about 6,000Angstrom units.

10. A process for the formation of a homopolymer of alpha,alpha'-bis(4acetoxy 3 methoxybenzylidene) pbenzenediacetonitrile which comprisessubjecting the benzenediacetonitrile to radiant energy of a wave lengthless than about 6,000 Angstrom units.

11. A process for the formation of a homopolymer of alpha,alph a 'bis(4acetoxy 3 methoxybenzylidene)- p-benzenediacetonitrile which comprisessubjecting the benzenediacetonitrile to incandescent light.

References Cited by the Examiner UNITED STATES PATENTS 2,448,755 9/1948Zellner 26078.4

2,971,977 2/1961 Kolb 26078.4

3,097,227 7/ 1963 Williams 260465 FOREIGN PATENTS 1,086,553 8/1960Germany.

OTHER REFERENCES Hoi et al.: Rec. Trav. Chem, vol. 74, pages 1119-24(1955).

Waldmann et al.: Ann, vol. 527, pages 183-9, 1957.

Kauifman: Ber. der Deut. Chem, France, vol. 23, pp. 636-642.

JOSEPH L. SCHOFER, Primary Examiner.

DONALD E. CZAJA, L. WOLF, Assistant Examiners.

1. A HOMOPOLYMER OF A DIBENZYLIDENEBENZENEDIACETONITRILE HAVING AMOLECULAR WEIGHT OF AT LEAST ABOUT 3,000.